Rustman

I know this has been discussed before, but I couldn't find it with the search.

What temperatures do the 1/4 and 3/4 markings represent on a 66 temperature gauge?

65GGvert

It's not a linear gauge (or sender). If you check it with an IR gun, you can see what the temperatures represent. The center is 210 on a 66 and the upper 240, but that doesn't mean the 3/4 line is 225.

65GGvert

I should add, that doesn't mean 210 is 210 either, unless you have verified it. Same with 240. The sensors vary greatly.

CaveCreekChump

I have only found one sending unit that allows the mid-year Corvette temp gauges to show accurate readings. That is the Burroughs TU5 from Advance Auto

leif.anderson93

Wells TU5 from Auto Zone...same, same.

CaveCreekChump

Auto Zone is correct, my mistake. However, a search for TU5 on their website shows that the brand name is now "Duralast".

65GGvert

Duralast TU5 is what I use also, 180 is 180 with those in my experience.

Gary's '66

So what exactly DO the 1/4 marks represent? Not trying to be a smart a$$ 'cause I've often wondered about those marks as well. Your explanation is kind of confusing to me.
I've often thought of the gauge as reading, like say, the gas gauge but from what you've written it sounds as though it doesn't.
You say "its not a linear gauge (or sender)" but it uses a sender at the thermostat housing.

leif.anderson93

[QUOTE=CaveCreekChump;1587443115]Auto Zone is correct, my mistake. However, a search for TU5 on their website shows that the brand name is now "Duralast".[/QUOTEs
Duralast is the brand name on the box, but Auto Zone reboxs Wells products. The TU5 is made for them by Wells.

Rustman

Well I just had my gauges restored and was curious what the temperatures might be. It never read hot before the restore with an original sender and now the gauge reads a tick above the 1/4 marker when IR gun shows ~180 on the waterneck. (can't remember where it read before the gauges were restored). Was just curious if this was good.

rongold

On my 67 427 with an original OEM Delco sending unit, the first line (1/4 scale) is exactly 180* as read with an IR gun.

65GGvert

The sender is what isn't linear. One half the resistance doesn't correlate to one half the degrees temp. Your best bet is to get it to "normal" in the middle and judge whether it's hot or cold off of that. Use an IR gun and shoot what the temp is at any place on the gauge and take note. I have a 65 and the center mark is marked 180 and the TU5 has the correct resistance to make that happen. It was intended to show you the car was getting hot, not to give you an exact temp like the newer cars do. In 66 the used the same gauge and sending unit, but changed the center mark reading to 210 because a lot of people thought anything over 180 was too hot.





PS, if it was linear it wouldn't be 80 degrees from the bottom (100 up to 180) and 60 degrees from 180 (up to 240) when 180 is the center mark.

Gary's '66

I've checked mine with a gun as well. When the gauge shows 210° I'm getting pretty close, give or take 5°, to that reading at the upper hose about 6" from the T stat housing with my gun.
When the gauge is reading slightly to the right of mid way between the 1/4 and the 210° mark (I'd say around 11:00) my gun reads 180-190° give or take 5° which, in my mind would seem about right.
So, I guess where it gets confusing for me is the calibration factor AFTER the 210° mark, which of course, is when I start getting a bit nervous.